A service call on a high-rise installation
At AirGreen , we are often called upon to work on complex installations. This was the case here, in a typical red brick duplex in the Lachine district, where a Gree wall-mounted heat pump was installed more than three meters above the ground, attached to wall brackets above an exterior staircase. The client had reported that her heat pump had not produced heat for several days, despite an operating indicator light being lit.
This type of installation, exposed to wind and climatic variations, puts a strain on the wall units. A quick inspection was necessary to avoid a more serious breakdown.
Diagnosis: A faulty reverse cycle and a defrost problem
Once on site, our technician Hugo performed a series of tests on the system. The symptoms observed were typical of a reversing valve problem :
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The outdoor unit was working, but no heat was being transferred inside .
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In heating mode, the compressor seemed to start correctly, but the indoor fan was blowing cold air .
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After a few minutes, the heat pump would go into standby, a sign of a bad feedback signal from the defrost sensor.
The analysis confirmed two causes: a mechanically blocked four-way valve and a faulty defrost sensor preventing the machine from switching properly between modes.
Repair steps: attention to detail and safety at height
The work on this wall unit required great caution . Working on a high-rise facade, Hugo set up portable scaffolding to safely access the unit. The repair steps followed our AirGreen protocol:
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Complete power off and electrical check.
The power was turned off, and the circuit checked to prevent accidental power surges. -
Draining the refrigerant and dismantling the housing.
We recovered the R-410A gas in a recovery cylinder, in accordance with environmental standards. -
Replacing the reversing valve.
After disassembly, the four-way valve was replaced with an original Gree part. A clean torch weld ensured a perfect seal. -
Change of the defrost probe and recalibration.
The new probe was installed and tested at different temperatures to validate correct frost detection. -
Gas refill and pressure test.
The system was re-evacuated and then recharged to the exact amount prescribed by the manufacturer. -
Comprehensive performance testing.
The compressor, valve and defrost cycle were tested under real conditions for over 30 minutes.
Results: restored heat and optimal functioning
As soon as the intervention was completed, the Gree heat pump resumed its normal performance. The customer noticed immediate heat production , with a blown air temperature reaching 43°C at the outlet of the indoor unit.
The device now works with:
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A responsive and quiet reversing valve ,
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A regular defrost cycle ,
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And stable power consumption .
We also slightly repositioned the exterior ducts to promote better drainage of condensate during winter cycles.
The challenges of high-rise wall installations in Montreal
Wall installations attached to duplex or triplex facades, very common in Lachine , LaSalle or Verdun , require special attention. Direct exposure to the elements — rain, ice, wind — can accelerate the wear of mechanical and electrical components.
At AirGreen, we recommend:
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An annual inspection before each winter,
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A spring cleaning of the condenser ,
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And a drainage check to avoid water backups.
These simple actions significantly extend the lifespan of a heat pump, while ensuring optimal energy efficiency.
AirGreen expertise: safety, reliability and performance
Our team has the equipment and expertise to work on all types of installations, even the most complex. Whether on narrow balconies, flat roofs, or high-rise facades, we adhere to the most rigorous safety standards and technical procedures .
Our technicians are certified to work on all major brands on the market — Gree, Fujitsu, Midea, Sharp, Lennox, Bosch, Goodman and many others.
In Montreal , Laval , on the North Shore and on the South Shore , AirGreen remains the trusted choice for fast and lasting HVAC repairs .